There has been conventionally known a process for an object to-be-processed, for example, a cleaning process for a semiconductor wafer (hereinafter, called “wafer”) or a glass substrate, using a mixed liquid prepared by mixing a plurality of different liquids. Generally, a liquid processing apparatus for processing an object to-be-processed, such as a wafer or a glass substrate, is provided with a plurality of processing units that forms a processing chamber so that the objects to-be-processed are sequentially processed in each processing unit. See, for example, Japanese Patent Laid-open Publication No. HEI 6-204201.
In the liquid processing apparatus disclosed in Japanese Patent Application Laid Open No. HEI 6-204201, liquid supply devices supplying a mixed liquid prepared by mixing different liquids are allocated to each corresponding processing unit. As a result, the liquid processing apparatus is configured to supply liquid from corresponding liquid supply device to the corresponding processing unit, according to the consumed amount of liquid in each processing unit. However, the concentrations of mixed liquids supplied from the plurality of liquid supply devices are different each other and the processing levels of objects to-be-processed processed in each different processing unit varies. Also, the configuration and control of the liquid processing apparatus tend to be complicated.
Also, in a liquid processing of objects to-be-processed by means of liquid, especially a chemical liquid, it is a big issue to save liquids from the viewpoints of reducing the process cost and the environmental maintenance.